Nickel and palladium .alpha.-diimine complexes are known catalysts for the polymerization of various olefins, including cyclopentene itself, see for instance World Patent Application 96/23010. However, methods for polymerization of various substituted cyclopentenes have not been reported with such catalysts.
Homopolymers of 3-methylcyclopentene have been reported, see for instance J. Boor, et al., Die Makromolekulare Chemie, vol. 90, p. 26-37 (1966).
World Patent Applications 96/23010 and 98/27124, and U.S. Pat. No. 5,880,241 describe homopolycyclopentenes which are melt processible.